STEWART, J., CLARKE, A.A. and CHEN, R., 2007. An experimental study of the dual-fuel performance of a small compression ignition diesel engine operating with three gaseous fuels. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 221(8), pp. 943-956.

Abstract:

A dual-fuel engine is a compression ignition (CI) engine where the primary gaseous
fuel source is premixed with air as it enters the combustion chamber. This homogenous mixture
is ignited by a small quantity of diesel, the ‘pilot’, that is injected towards the end of the
compression stroke. In the present study, a direct-injection CI engine, was fuelled with three
different gaseous fuels: methane, propane, and butane. The engine performance at various
gaseous concentrations was recorded at 1500 r/min and quarter, half, and three-quarters
relative to full a load of 18.7 kW. In order to investigate the combustion performance, a novel
three-zone heat release rate analysis was applied to the data. The resulting heat release rate data
are used to aid understanding of the performance characteristics of the engine in dual-fuel mode.
Data are presented for the heat release rates, effects of engine load and speed, brake specific
energy consumption of the engine, and combustion phasing of the three different primary
gaseous fuels.
Methane permitted the maximum energy substitution, relative to diesel, and yielded the
most significant reductions in CO2. However, propane also had significant reductions in CO2 but
had an increased diffusional combustion stage which may lend itself to the modern high-speed
direct-injection engine.